1. Field of the Invention
The invention relates to a display device, and more particularly to a display device which is capable of providing a driving current, which is irrelevant to a threshold voltage of a transistor and a driving voltage of a light-emitting diode, to drive the light-emitting diode.
2. Description of the Related Art
Organic light-emitting diode (OLED) display devices have some advantages, such as a slight size, light weight, high light-emitting efficiency, low driving voltage, and a simple process. Thus, recently, OLED display devices are one of the popular types of flat display devices. According to driving methods, OLED display devices are divided into passive-matrix OLED display (PM-OLED) devices and active-matrix OLED (AM-OLED) display devices. AM-OLED display devices emit light by current driving and use at least one thin-film transistor (TFT) to serve as a switch. The TFT adjusts a current according to the voltage stored in a storage capacitor to control gray levels in different pixel areas.
Further, according to panel process techniques, AM-OLED display devices are divided into P-type driving display devices and N-type driving display devices. However, threshold voltages of TFTs and driving voltages of OLEDs in an active matrix vary as time goes by, resulting in a mura phenomenon to occur in the AM-OLED display devices.